Hierarchical porous carbon derived from recycled bamboo waste as supercapacitors electrodes based on FeCl3-catalyzed hydrothermal pretreatment: Pore regulation and high-performance analysis

Summary Herein, a green and novel FeCl 3 -catalyzed hydrothermal pretreatment method is adopted to convert the bamboo shavings waste into bamboo-based hierarchical porous carbons (BHPCs) with ultra-high specific surface area and excellent electrochemical properties. Utilizing this mild FeCl 3 catalyst can not only promote the dehydration, condensation, and carbonization of bamboo shavings to catalyze the formation of hydrochar, but also facilitate the development of the pore structure of hydrochar. Moreover, the effects of different FeCl 3 solution concentrations, activation temperatures, and KOH/hydrochar ratios on the pore structure of BHPCs and the electrochemical performance of supercapacitors are thoroughly investigated. Compared with the hydrothermal carbonization without FeCl 3 addition, the BHPCs (1-BHPC-800-5) electrode materials obtained by FeCl 3 -catalyzed hydrothermal pretreatment have superior specific surface area (up to 3688 m 2 g −1 ) and total pore volume (as high as 1.989 cm 3 g −1 ). Meanwhile, the best-performing 1-BHPC-800-5 demonstrates outstanding electrochemical performance in supercapacitor applications, providing a pleasant capacitance of 378 F g −1 at 0.5 A g −1 and capacitance retention of 96.6% after 10 000 charge/discharge cycles at 5.0 A g −1 in 6.0 M KOH electrolyte. The energy density can reach 10.3 Wh kg −1 at a power density of 250 W kg −1 in a two-electrode system. Therefore, this novel and efficient catalytic hydrothermal pretreatment method offers a promising prospect for converting waste biomass into hierarchical porous carbon materials with a large specific surface area and excellent electrochemical properties. Key Points Adopting a green FeCl 3 -catalyzed hydrothermal pretreatment method to convert bamboo shavings waste into BHPCs. BHPCs exhibit a hierarchical porous structure and an ultra-high specific surface area (up to 3688 m 2 g −1 ). A very high capacitive performance (378 F g −1 at 0.5 Ag −1 ) is achieved. The excellent rate performance (nearly 71% capacitance retention), outstanding cycle stability (capacitance retention of 96.6% after 10 000 charge/discharge cycles) and large energy density (10.3 Wh kg −1 at 250 W kg −1 ) are demonstrated.